26 carver montego prop help needed

[bolo78910]

hello again guys, my carver montego is only givine me 25 knots at 4100 rpm using a four blade aluminium 16 pitch.

boat was properly trimed, water was calm. engine is a new reman just broken in. the weight of this boat is almost 6000 lbs merc 5.7 with a extra horsepower cam install, should i drop down to a 51x15 3 blade ect . bottom of the boat is also clean just painted.

i will be waiting for some input on this, thanks

 

[steelespike]

Re: 26 carver montego prop help needed

A 1" change in pitch will give about 200 rpm.I don't know your recommended
rpm.How did it used to go with the 16? The cam may not do much if not matched with carb and manifold.Also may require a distributor and timing curve change.Also a slim possibility the valves might float with a severe cam.

 

[bolo78910]

Re: 26 carver montego prop help needed

thanks witrh the 16 pitch 4 blade my w o t is 4100 25 knots via gps with only me on the boat. i was told the mercruiser 5.7 should be around 4600 wot rpm . maybe a 16 pitch three blade , or a 15x15 three will do me good your thought.

 

[Tail_Gunner]

Re: 26 carver montego prop help needed

Ill bite..what year is the boat and drive type a bravo i assume...based on your number's maybe a 11-12 pitch blade ss for a start//

 

[bolo78910]

Re: 26 carver montego prop help needed

1985 carver montego 26

 

[Tail_Gunner]

Re: 26 carver montego prop help needed

1985 carver montego 26

What type of drive?

 

[bolo78910]

Re: 26 carver montego prop help needed

oops sorry, alpha one gen one

 

[Tail_Gunner]

Re: 26 carver montego prop help needed

Ok the boat is doing 4100 with a 16p 4blade alum so lets try this as a 3 blade for easier comparison and more availability..so lets jump to 16 @ 4200 picking up a 100 for losing the 4 blade..

1. 16@4200 rpm
2. 15@4400 rpm
3.14@4600 rpm..........
4.15@4800 rpm

Those numbers should work for 3 blade alum's, you should however be very careful on your tach's accuracy and your engines state of tune. You may also want to the I/O fourms and find out the engines RPM band and just what type of drive it is.... there are a few...Why someone would cam a boat is a little suspious they operate in a very narrow or restricted enviroment you may also share that with the I/O guy's...Some very well informed people in there.. I first would clear that up to your satisfaction and then get a prop.

Umm they can be a bit frank..but you will not find any better advice anywhere and its free...

http://boatpropellers.iboats.com/Me...r=1985&**********=126824546&*******=214798065

 

[bolo78910]

Re: 26 carver montego prop help needed

thanks much i will make sure carb and everything else is up to speck, thanks again.

 

[APPALOOSA2]

Re: 26 carver montego prop help needed

I had similiar size boat with the same engine & outdrive and used a 3 blade 16 x16. Boat should top out about 38-40 mph and rpms will be in spec.

 

[bolo78910]

Re: 26 carver montego prop help needed

r u serious my 26 foot carver montego weight over 5000 lbs should do over 36 to 40 knots, wow. what carb r u running ??? share some more info please . right now i have a 17 pitch mirage with three vent holes that has plugs, i want to give it a try i know the 17 pitch is the same as a 16 pitch four blade.

 

[Tail_Gunner]

Re: 26 carver montego prop help needed

r u serious my 26 foot carver montego weight over 5000 lbs should do over 36 to 40 knots, wow. what carb r u running ??? share some more info please . right now i have a 17 pitch mirage with three vent holes that has plugs, i want to give it a try i know the 17 pitch is the same as a 16 pitch four blade.

 

[bolo78910]

Re: 26 carver montego prop help needed

lol my carver will never do over 30 with a merc 5. 7 let me just stop dreaming.

 

[Neverhome]

Re: 26 carver montego prop help needed

I know nothing about the cam situation but I have a 23' Trophy 2359, that weighs in around 7,000 lbs fully loaded with fuel, gear, water and two people.
I also have the 5.7, Alpha One, Gen Two. My top speed is just about 30.5
MPH at 4500 RPM's using a three bladed 14x13 prop. I tried several including a four blade but just couldn't hit the correct RPM range until I installed this prop. It gives me a good hole shot and very good manuverability at the dock.

Neverhome

 

[bolo78910]

Re: 26 carver montego prop help needed

k so maybe i just need to drop down to a 15 pitch prop then. and give it a try.

 

[APPALOOSA2]

Re: 26 carver montego prop help needed

Like I said before I had a 27' 6200 lbs with a 5.7 carbed and alpha 1 and the 16 x16 3 blade did 38-41 WOT depending on water condition, at 3000 rpm she would cruise 22mph and at 3350 she would do 24-26 mph.
Seemed pretty fuel efficent for 27' of boat. Never had a problem getting on plane.

 

[bolo78910]

Re: 26 carver montego prop help needed

those are some very good numbers. it seems by boat might have a carb issue , so right now i am doing some trouble shooting. i also pretty sure the mercury 17 pitch ss is not going to cut it also.
any one have good 15 pitch and want to trade for my 17 ss mercury i dont remember the number right now but i kno it start 48-####17 lol

if you got a good 15 pitch we can do buisness trade doent matter if yours is aluminium as long as it is not ding up or rebuild, mines has no ding.

 

[bolo78910]

Re: 26 carver montego prop help needed

up date here guys i just install a spanking new stainless merage plus 15x15 prop and only can get 4000 rpm at 25 or 26 knots gps reading . with 16 pitch four blade i was getting the same rpm 17 pitch ss i get the same rpm now i am down two pitch and the same result , please help me answer these ?????

is my tach shot cant go over 4000 rpm?

does a bad coil has anything to do with rpm?

will a carburator stuck me at 4000 rpm??

will a distributor not advancing properly stuck me at 4000 rpm?


thanks for any inputs.